1970 Chevelle Quarter Panel Repair - Widening The House

In this part of our ’70 Chevelle project, we test-fit new quarter-panels and our wheelhouses have a growth spurt to make way for big rubber.

While this project may seem fairly daunting for many readers because of how far gone this ’70 Chevelle convertible was, it does offer some great information and tips that can be handy for any restoration project. And to be perfectly honest, writing these stories so far has been a bit difficult. When it comes to our tech articles, Super Chevy always tries to make sure that everyonefrom the guy hammering away in his own garage to the more affluent reader who can write a check to a buildercan take something useful away from a story.

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In our last installment, we showed where custom metal work can be needed with an especially rusty car, and to help you understand exactly what goes into it. This go around, we’re getting into some more normal repairs, like fitting our new decklid, quarter-panels, and doors. Along with that, we’ve got to expand the wheelhouses to fit our much wider Boze wheels and Nitto rubber, so our 572 big-block will have plenty of grip.

The crew at Classic Automotive Restoration Specialists (CARS) has been cutting and welding on our Chevelle for a whole year now. While it might not look like much has been accomplished, significant progress has been made. When we started, the car’s overall structure was shaky at best, with the convertible top frame serving as a major structural member in support of the rapidly deteriorating body.

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Things are now much more solid. Our new Goodmark one-piece floor is in place, bolstering structural integrity tenfold over what it was. Where before the top couldn’t even be unlatched because it was under so much load and the doors wouldn’t open, now the doors open and close like new, and we actually could unlatch the top to fully inspect its condition.

Speaking of metal, the folks at Goodmark Industries have been keeping us well-supplied with fresh steel to transplant onto our rusty A-body. Goodmark offers a wide range of metal for various GM, Ford, and Mopar makes. If you’re in need of some repair panels for your car, check out its website at www.goodmark.com.

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1970 Chevelle Quarter Panel Repair - Widening The House

The first order of business was to remove the old door, and transfer the latch mechanism to our new Goodmark door. Since we're replacing more than just a quarter-panel, it's necessary to mock-up the new door and decklid so we can make sure all panel gaps and alignment are correct.

1 Goodmark also supplied us with new door hinges, which we also used for mocking-up everything so we'd know there was no sag in the door. If you're replacing just the quarter-panel, make sure your hinges are in good working order, or go ahead and rebuild them first before fitting the new quarter. This way you'll know everything's going to line up correctly.

2 When we lined up the new door, we noticed the bottom edge wasn't shaped exactly like the original. This is a common occurrence with replacement sheetmetal, due to the stamping process. We'll show how to correct this in a later story.

3 Here, Tommy Barber is installing the new decklid so we can get the quarter-panel lined up. With so much sheetmetal being replaced, fitment and alignment are critical issues that have to be paid close attention to. If even a seemingly minor part like our decklid isn't aligned correctly, it'll throw off our quarter-panel alignment--which'll throw off the door alignment, which will then throw off the front fender alignment.

4 To make removing the old panel easier, Tommy uses a "can opener" blade on an air chisel to remove most of the old metal, leaving the edges left to have their spot welds drilled out so the rest can be pried off. This also makes getting to the factory spot welds easier.

5 Here's a good look inside with most of the factory quarter removed. Thanks to its salty northern life, there's not much left of the outer wheelhouse. That's OK, as we've got new metal to replace it with.

6 With more spot welds to drill, Tommy breaks out the plasma cutter and trims away most of the old outer wheelhouse. This could also be done with a cutoff wheel if you don't have a plasma cutter to play with.

7 This trunk/deck brace is spot welded onto the wheelhouse (the small rectangle of steel at the bottom) so after the factory welds are drilled out, we'll clean up and prep the piece for modification and rewelding.

8 The quarter on a '70 Chevelle goes all the way into the door opening. Here Tommy is using an air chisel to break loose the seam between the quarter and sill area after the spot welds have been drilled out.

9 Gratuitous new quarter-panel shot! Slowly but surely our Chevelle is starting to look like a whole car again. This gives you an idea of how much metal is in one quarter-panel, and its significance in the body's structure, especially in the case of a convertible.

10 Here's a good close up that shows how much of the quarter goes into the door opening.

11 In the Astroventilation area of the quarter is this galvanized steel brace. Being galvanized, this part was well protected against the rust that ate away at the rest of the car. We'll clean this up, coat it with some weld-through zinc primer, and install the new quarter on top of it.

12 Back near the decklid area, there's a factory seam that has to be drilled out. Tommy uses a MAP gas torch (MAP gas comes in yellow canisters and burns hotter than regular propane, which comes in blue bottles) to melt out the factory lead seam filler. Always do lead cooking in a well-ventilated area and with a mask so you don't inhale any harmful lead vapors.

13 When our car was assembled at the factory, too much heat was used to weld these pieces together. That is why the surface has so many dips and rises in it.

14 With the quarter-panel removed, this wonderful surprise greeted us. Damage like this is usually unique to convertibles because of leakage from water running down the top. We'll clean the area of rust, then patch in new steel where the old is too thin or rusty.

15 We set the new inner wheelhouse to start sizing things up for the mini-tub operation, and discovered that our inner and outer wheelhouses didn't match what were on the car. A call to the Goodmark tech line revealed that convertibles use a unique wheelhouse not shared with coupes and sedans. This put us into a quandary, but we were soon able to solve the problem. More on that later.

16 Here, Tommy has marked the areas of the trunk floor that need to be trimmed away for mini-tubbing. To save some time forming metal, he'll save the original lip of the floor, remove the necessary metal behind it, then weld the lip back on to the pan.

17 With everything marked fore and aft, the cutoff wheel sends sparks flying. No reminders about eye protection here, but we'll give a friendly nod to making sure the area around where you're cutting is grease and solvent free so nothing takes aflame.

18 To make enough room, the pan had to be cut back almost to the framerail. We'll still leave some clearance between the rail and floor so they won't rub together and make trouble later after the car's been finished.

19 One trouble spot with narrowing the floor is this area where a brace extends across the width of the pan. This area will be dressed and capped off before the pan lip is welded back in place.

20 We used one of our Boze wheels to mock-up how deep the wheel would mount in the well, and clamped the floor lip back in place for tack welding. Since we weren't using an aftermarket, premeasured mini-tub kit, it was necessary to use a wheel for checking the measurement of how much we'd need to widen the wheelhouse.

21 Everything checked out, so Tommy began welding the floor lip back into place.

22 After the welds are cleaned and dressed, this area will be all set.

23 Towards the front of the floor where the lip curves around, we needed some metal mods and custom fabricating. Here, a metal stretcher is used to form and widen a piece we'll be using to finish the lip.

24 To get this part right, a piece of heavy masking paper and some tape are used to mock-up the length and bends.

25 Here you can see the correct convertible wheelhouse on the left, and the coupe/sedan wheelhouse on the right. Note the flat spots on the ragtop piece versus the coupe/sedan one. Because of the low number of convertibles built, and low demand for related unique parts, Goodmark hasn't added this part to its catalog yet. In fact, the only source for this part is Dynacorn. A call to Dynacorn's Jim Christina saved the day, and we soon had the correct wheelhouses to keep our installation going. If Goodmark doesn't happen to have the parts you need in their catalog yet, give the folks at Dynacorn a call, or visit www.dynacorn.com.

26 The Dynacorn wheelhouses come preassembled. Here, CARS owner Jim Barber fits the new piece in place for measurement.

27 To make enough room for the new rear tire/wheel combo, the wheelhouse will need to be widened two inches. So the fitment with the quarter isn't affected, we'll add the metal to the inside half of the assembly. This will have it butted right next to the floorpan.

28 First the housing is split down the middle of the inner half using a cutoff wheel.

29 Using a strip of steel, Tommy clamps the expansion piece in place so it can be tack-welded to the house. You want just enough welds to hold the strip firmly in place, but not create more work for yourself if you need to shift things around. For this process we're using a MIG-welder set for the appropriate steel thickness.

30 Next, the rest of the house is aligned and clamped for welding. Once it's set, we'll use the MIG to tack it in place.

31 Because the hump/curvature of the inner wheelhouse is being shifted over so much, the mounting tab on the brace will need to be shifted upward so it can be properly attached to the house. The spot welds on the back side have already been drilled out, and an air chisel is being used (gently) to separate the two pieces.

32 With the mounting tab out of the way, the freshly widened wheelhouse is set in place so we can mark where the tab should go, and see if any further mods are needed.

33 Because the angle the tab will attach at is going to change, this triangular notch will need to be cut out so it can bend to the proper angle.

34 With the slice made, you can see where the tab was bent inward for the necessary angle so it can attach to the wheelhouse.

35 If you're doing this work at home or in a private shop, having plenty of welding clamps will save you time and a lot of frustration. Here you can see the mounting tab clamped back in place on the support, and in full contact with the wheelhouse just like it was originally.

36 A couple of tacks with the MIG and the tab is secure. After everything with the wheelhouse is double checked and the quarter-panel refitted, we'll tack the wheelhouse in place too.

37 Here's the whole picture. Once the finish welding and rust cleanup is done, we'll be ready for the new quarter-panel to be welded in place. Once painted this will be a "stealth" mini-tub job, and require closer examination before anyone with less than a trained eye will notice we've added some extra space here.